The City Naturalist

City Naturalist

Sweet Gum Tree

Article and Photos by Leslie Day

SWEETGUM TREE Liquidambar styraciflua L.
Common Names: Sweet gum, Redgum, Star-leaved gum, Bilsted, Alligator Tree and Liquidambar.

DESCRIPTION: The sweet gum is a large, native, aromatic tree becoming 60 to 120 feet in height, with a trunk from 2 to 4 feet in diameter. In the open it develops a very symmetric pyramidal crown, with spreading and almost horizontal branches persisting rather low on the tapering, continuous trunk. When growing in the forests, the trunks are straight and clean, with a rather small lofty crown.

LOCALLY:There are many sweet gum trees in Riverside Park. There are two sweet gum trees just outside the fence on the northern border of the ball field at the Boat Basin. In December, when all the leaves have fallen, if you look up into the trees you see hundreds of spiny seedballs hanging from their pendant-like stems. These and other kinds of seeds which hang and remain on the trees through the winter look like models of the original Christmas tree decorations. We have seen squirrels holding these spiky fruits and tearing them open with their teeth to get at the winged seeds inside.

If you take some of the closed-up, newly fallen, green or brown seedballs into your home, within a short time they open and dispel the seeds. Put them in a ziplock baggie with a wet paper towel at the base, and in a few months they will germinate. You will be able to grow your own sweet gum tree! In October and November the fallen leaves are beautiful red and gold stars that cover the park walkways and grasses. In every season the Liquidambar is a beautiful tree.

LEAVES: The leaves are alternate, simple, distinctly and beautifully star-shaped, maple-like and quite pleasantly fragrant when crushed. They are usually 5-lobed with tapering, pointed lobes which are finely toothed on the margins with 5 main veins from a notched base. The leaves are shiny dark green above, paler beneath, turning red and gold in autumn.

SEEDS: A long-stalked pendulant seedball composed of many individual fruits each ending in 2 long curved prickly points. Each compartment of these seedballs contains many small, winged seeds. The seedballs mature in autumn and persist into winter. The sharp, pointed, woody capsules give them a spiny appearance. The seeds are eaten by songbirds and squirrels here in New York City and by wild turkey, chipmunks, songbirds, squirrels and bobwhite in rural and suburban areas.

BARK: Gray, deeply furrowed into narrow, scaly ridges (hence the name Alligator Tree).

RANGE: Extreme Sw. Connecticut south to Central Florida, west to E. Texas, and north to S. Illinois.

USES: Both common and scientific names allude to the sap that exudes from cuts in the bark. Hardened clumps of this gum are chewed by some people, as it was chewed by Native Americans and the early pioneers. In pioneer days, the gum was obtained from the trunks by peeling the bark and scraping off the resinlike solid. This gum was used medicinally as well as for chewing gum. Commercial storax, a fragrant resin used in perfumes and medicines, is from the related Oriental sweet gum (Liquidambar orientalis Mill.) of western Asia.

An important timber tree, sweet gum is second in production only to oaks among hardwoods. Sweet gum lumber is used for interiors, woodenware, boats, toys, boxes and fuel.

HISTORY: The sweet gum is a living fossil. Today there are three existing species of Liquidambar: one in Formosa, one in Turkey, and one native to America. Twenty extinct species are known, the oldest found in the Upper Eocene rocks of Greenland, in an age when that continent had a subtropical climate, some 55,000,000 years ago. Later fossils turned up in Italy, Siberia, Colorado, and in great numbers in the Miocene lake beds of Switzerland. From the Pleistocene or Glacial Period, we have found sweet gum leaves in much the same regions the living species are found in today.

The American species was described to Europeans by Francisco Hernandez, the first great herbalist of Mexico, in about 1651. He speaks of it as having leaves "almost like those of a maple," and a resin of which the "nature is hot in the third order, and dry, and added to tobacco, it strengthens the head, belly and heart, induces sleep, and alleviates pains in the head that are caused by colds. Alone, it dissipates humors, relieves pain, cures eruptions of the skin...and dissipates tumors beyond belief."

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